198 The American Naturalist. [February, 
These pith disks may also be used to introduce into the serous cavi- 
ties of higher organisms and left long enough to become filled with 
entrapped leucocytes or lymph cells. I anticipate that such a method 
would greatly facilitate the study of karyokinesis and its technique of 
staining in connection with wandering cells in wounds. 
The novelty and simplicity of this new method, as well as its wide 
range of applicability, impels me to promptly offer it to my fellow- 
naturalists as a procedure that will in many cases be found to materi- 
ally facilitate their work, especially the work of those engaged in the 
study of Protozoa, or of very minute ova or larve. A very simple 
form of this apparatus, for holding the filtering paper in position, is 
being made and offered for sale by Chas. Lentz & Sons, of Philadelphia. 
Dee. 9th, 1894. 
Joun A. RYDER. 
